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1817 lines
45 KiB
1817 lines
45 KiB
// SPDX-License-Identifier: GPL-2.0-only |
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/* |
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* linux/kernel/exit.c |
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* |
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* Copyright (C) 1991, 1992 Linus Torvalds |
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*/ |
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|
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#include <linux/mm.h> |
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#include <linux/slab.h> |
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#include <linux/sched/autogroup.h> |
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#include <linux/sched/mm.h> |
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#include <linux/sched/stat.h> |
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#include <linux/sched/task.h> |
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#include <linux/sched/task_stack.h> |
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#include <linux/sched/cputime.h> |
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#include <linux/interrupt.h> |
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#include <linux/module.h> |
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#include <linux/capability.h> |
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#include <linux/completion.h> |
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#include <linux/personality.h> |
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#include <linux/tty.h> |
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#include <linux/iocontext.h> |
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#include <linux/key.h> |
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#include <linux/cpu.h> |
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#include <linux/acct.h> |
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#include <linux/tsacct_kern.h> |
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#include <linux/file.h> |
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#include <linux/fdtable.h> |
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#include <linux/freezer.h> |
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#include <linux/binfmts.h> |
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#include <linux/nsproxy.h> |
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#include <linux/pid_namespace.h> |
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#include <linux/ptrace.h> |
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#include <linux/profile.h> |
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#include <linux/mount.h> |
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#include <linux/proc_fs.h> |
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#include <linux/kthread.h> |
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#include <linux/mempolicy.h> |
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#include <linux/taskstats_kern.h> |
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#include <linux/delayacct.h> |
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#include <linux/cgroup.h> |
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#include <linux/syscalls.h> |
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#include <linux/signal.h> |
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#include <linux/posix-timers.h> |
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#include <linux/cn_proc.h> |
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#include <linux/mutex.h> |
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#include <linux/futex.h> |
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#include <linux/pipe_fs_i.h> |
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#include <linux/audit.h> /* for audit_free() */ |
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#include <linux/resource.h> |
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#include <linux/blkdev.h> |
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#include <linux/task_io_accounting_ops.h> |
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#include <linux/tracehook.h> |
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#include <linux/fs_struct.h> |
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#include <linux/init_task.h> |
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#include <linux/perf_event.h> |
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#include <trace/events/sched.h> |
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#include <linux/hw_breakpoint.h> |
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#include <linux/oom.h> |
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#include <linux/writeback.h> |
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#include <linux/shm.h> |
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#include <linux/kcov.h> |
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#include <linux/random.h> |
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#include <linux/rcuwait.h> |
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#include <linux/compat.h> |
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#include <linux/io_uring.h> |
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|
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#include <linux/uaccess.h> |
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#include <asm/unistd.h> |
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#include <asm/mmu_context.h> |
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|
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static void __unhash_process(struct task_struct *p, bool group_dead) |
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{ |
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nr_threads--; |
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detach_pid(p, PIDTYPE_PID); |
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if (group_dead) { |
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detach_pid(p, PIDTYPE_TGID); |
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detach_pid(p, PIDTYPE_PGID); |
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detach_pid(p, PIDTYPE_SID); |
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|
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list_del_rcu(&p->tasks); |
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list_del_init(&p->sibling); |
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__this_cpu_dec(process_counts); |
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} |
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list_del_rcu(&p->thread_group); |
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list_del_rcu(&p->thread_node); |
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} |
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|
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/* |
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* This function expects the tasklist_lock write-locked. |
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*/ |
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static void __exit_signal(struct task_struct *tsk) |
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{ |
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struct signal_struct *sig = tsk->signal; |
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bool group_dead = thread_group_leader(tsk); |
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struct sighand_struct *sighand; |
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struct tty_struct *tty; |
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u64 utime, stime; |
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sighand = rcu_dereference_check(tsk->sighand, |
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lockdep_tasklist_lock_is_held()); |
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spin_lock(&sighand->siglock); |
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|
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#ifdef CONFIG_POSIX_TIMERS |
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posix_cpu_timers_exit(tsk); |
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if (group_dead) |
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posix_cpu_timers_exit_group(tsk); |
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#endif |
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|
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if (group_dead) { |
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tty = sig->tty; |
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sig->tty = NULL; |
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} else { |
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/* |
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* If there is any task waiting for the group exit |
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* then notify it: |
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*/ |
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if (sig->notify_count > 0 && !--sig->notify_count) |
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wake_up_process(sig->group_exit_task); |
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|
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if (tsk == sig->curr_target) |
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sig->curr_target = next_thread(tsk); |
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} |
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|
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add_device_randomness((const void*) &tsk->se.sum_exec_runtime, |
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sizeof(unsigned long long)); |
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|
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/* |
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* Accumulate here the counters for all threads as they die. We could |
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* skip the group leader because it is the last user of signal_struct, |
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* but we want to avoid the race with thread_group_cputime() which can |
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* see the empty ->thread_head list. |
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*/ |
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task_cputime(tsk, &utime, &stime); |
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write_seqlock(&sig->stats_lock); |
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sig->utime += utime; |
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sig->stime += stime; |
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sig->gtime += task_gtime(tsk); |
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sig->min_flt += tsk->min_flt; |
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sig->maj_flt += tsk->maj_flt; |
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sig->nvcsw += tsk->nvcsw; |
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sig->nivcsw += tsk->nivcsw; |
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sig->inblock += task_io_get_inblock(tsk); |
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sig->oublock += task_io_get_oublock(tsk); |
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task_io_accounting_add(&sig->ioac, &tsk->ioac); |
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sig->sum_sched_runtime += tsk->se.sum_exec_runtime; |
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sig->nr_threads--; |
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__unhash_process(tsk, group_dead); |
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write_sequnlock(&sig->stats_lock); |
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|
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/* |
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* Do this under ->siglock, we can race with another thread |
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* doing sigqueue_free() if we have SIGQUEUE_PREALLOC signals. |
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*/ |
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flush_sigqueue(&tsk->pending); |
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tsk->sighand = NULL; |
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spin_unlock(&sighand->siglock); |
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|
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__cleanup_sighand(sighand); |
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clear_tsk_thread_flag(tsk, TIF_SIGPENDING); |
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if (group_dead) { |
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flush_sigqueue(&sig->shared_pending); |
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tty_kref_put(tty); |
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} |
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} |
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static void delayed_put_task_struct(struct rcu_head *rhp) |
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{ |
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struct task_struct *tsk = container_of(rhp, struct task_struct, rcu); |
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|
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perf_event_delayed_put(tsk); |
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trace_sched_process_free(tsk); |
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put_task_struct(tsk); |
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} |
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|
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void put_task_struct_rcu_user(struct task_struct *task) |
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{ |
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if (refcount_dec_and_test(&task->rcu_users)) |
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call_rcu(&task->rcu, delayed_put_task_struct); |
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} |
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|
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void release_task(struct task_struct *p) |
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{ |
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struct task_struct *leader; |
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struct pid *thread_pid; |
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int zap_leader; |
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repeat: |
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/* don't need to get the RCU readlock here - the process is dead and |
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* can't be modifying its own credentials. But shut RCU-lockdep up */ |
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rcu_read_lock(); |
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dec_rlimit_ucounts(task_ucounts(p), UCOUNT_RLIMIT_NPROC, 1); |
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rcu_read_unlock(); |
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cgroup_release(p); |
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write_lock_irq(&tasklist_lock); |
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ptrace_release_task(p); |
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thread_pid = get_pid(p->thread_pid); |
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__exit_signal(p); |
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|
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/* |
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* If we are the last non-leader member of the thread |
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* group, and the leader is zombie, then notify the |
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* group leader's parent process. (if it wants notification.) |
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*/ |
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zap_leader = 0; |
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leader = p->group_leader; |
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if (leader != p && thread_group_empty(leader) |
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&& leader->exit_state == EXIT_ZOMBIE) { |
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/* |
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* If we were the last child thread and the leader has |
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* exited already, and the leader's parent ignores SIGCHLD, |
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* then we are the one who should release the leader. |
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*/ |
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zap_leader = do_notify_parent(leader, leader->exit_signal); |
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if (zap_leader) |
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leader->exit_state = EXIT_DEAD; |
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} |
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|
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write_unlock_irq(&tasklist_lock); |
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seccomp_filter_release(p); |
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proc_flush_pid(thread_pid); |
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put_pid(thread_pid); |
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release_thread(p); |
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put_task_struct_rcu_user(p); |
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p = leader; |
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if (unlikely(zap_leader)) |
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goto repeat; |
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} |
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|
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int rcuwait_wake_up(struct rcuwait *w) |
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{ |
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int ret = 0; |
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struct task_struct *task; |
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|
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rcu_read_lock(); |
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|
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/* |
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* Order condition vs @task, such that everything prior to the load |
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* of @task is visible. This is the condition as to why the user called |
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* rcuwait_wake() in the first place. Pairs with set_current_state() |
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* barrier (A) in rcuwait_wait_event(). |
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* |
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* WAIT WAKE |
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* [S] tsk = current [S] cond = true |
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* MB (A) MB (B) |
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* [L] cond [L] tsk |
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*/ |
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smp_mb(); /* (B) */ |
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task = rcu_dereference(w->task); |
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if (task) |
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ret = wake_up_process(task); |
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rcu_read_unlock(); |
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return ret; |
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} |
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EXPORT_SYMBOL_GPL(rcuwait_wake_up); |
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|
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/* |
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* Determine if a process group is "orphaned", according to the POSIX |
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* definition in 2.2.2.52. Orphaned process groups are not to be affected |
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* by terminal-generated stop signals. Newly orphaned process groups are |
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* to receive a SIGHUP and a SIGCONT. |
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* |
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* "I ask you, have you ever known what it is to be an orphan?" |
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*/ |
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static int will_become_orphaned_pgrp(struct pid *pgrp, |
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struct task_struct *ignored_task) |
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{ |
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struct task_struct *p; |
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|
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do_each_pid_task(pgrp, PIDTYPE_PGID, p) { |
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if ((p == ignored_task) || |
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(p->exit_state && thread_group_empty(p)) || |
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is_global_init(p->real_parent)) |
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continue; |
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|
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if (task_pgrp(p->real_parent) != pgrp && |
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task_session(p->real_parent) == task_session(p)) |
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return 0; |
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} while_each_pid_task(pgrp, PIDTYPE_PGID, p); |
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|
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return 1; |
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} |
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|
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int is_current_pgrp_orphaned(void) |
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{ |
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int retval; |
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|
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read_lock(&tasklist_lock); |
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retval = will_become_orphaned_pgrp(task_pgrp(current), NULL); |
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read_unlock(&tasklist_lock); |
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return retval; |
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} |
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static bool has_stopped_jobs(struct pid *pgrp) |
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{ |
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struct task_struct *p; |
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|
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do_each_pid_task(pgrp, PIDTYPE_PGID, p) { |
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if (p->signal->flags & SIGNAL_STOP_STOPPED) |
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return true; |
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} while_each_pid_task(pgrp, PIDTYPE_PGID, p); |
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|
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return false; |
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} |
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|
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/* |
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* Check to see if any process groups have become orphaned as |
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* a result of our exiting, and if they have any stopped jobs, |
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* send them a SIGHUP and then a SIGCONT. (POSIX 3.2.2.2) |
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*/ |
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static void |
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kill_orphaned_pgrp(struct task_struct *tsk, struct task_struct *parent) |
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{ |
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struct pid *pgrp = task_pgrp(tsk); |
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struct task_struct *ignored_task = tsk; |
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|
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if (!parent) |
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/* exit: our father is in a different pgrp than |
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* we are and we were the only connection outside. |
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*/ |
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parent = tsk->real_parent; |
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else |
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/* reparent: our child is in a different pgrp than |
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* we are, and it was the only connection outside. |
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*/ |
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ignored_task = NULL; |
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|
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if (task_pgrp(parent) != pgrp && |
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task_session(parent) == task_session(tsk) && |
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will_become_orphaned_pgrp(pgrp, ignored_task) && |
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has_stopped_jobs(pgrp)) { |
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__kill_pgrp_info(SIGHUP, SEND_SIG_PRIV, pgrp); |
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__kill_pgrp_info(SIGCONT, SEND_SIG_PRIV, pgrp); |
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} |
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} |
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|
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#ifdef CONFIG_MEMCG |
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/* |
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* A task is exiting. If it owned this mm, find a new owner for the mm. |
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*/ |
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void mm_update_next_owner(struct mm_struct *mm) |
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{ |
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struct task_struct *c, *g, *p = current; |
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|
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retry: |
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/* |
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* If the exiting or execing task is not the owner, it's |
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* someone else's problem. |
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*/ |
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if (mm->owner != p) |
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return; |
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/* |
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* The current owner is exiting/execing and there are no other |
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* candidates. Do not leave the mm pointing to a possibly |
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* freed task structure. |
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*/ |
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if (atomic_read(&mm->mm_users) <= 1) { |
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WRITE_ONCE(mm->owner, NULL); |
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return; |
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} |
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|
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read_lock(&tasklist_lock); |
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/* |
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* Search in the children |
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*/ |
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list_for_each_entry(c, &p->children, sibling) { |
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if (c->mm == mm) |
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goto assign_new_owner; |
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} |
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|
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/* |
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* Search in the siblings |
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*/ |
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list_for_each_entry(c, &p->real_parent->children, sibling) { |
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if (c->mm == mm) |
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goto assign_new_owner; |
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} |
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|
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/* |
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* Search through everything else, we should not get here often. |
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*/ |
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for_each_process(g) { |
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if (g->flags & PF_KTHREAD) |
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continue; |
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for_each_thread(g, c) { |
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if (c->mm == mm) |
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goto assign_new_owner; |
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if (c->mm) |
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break; |
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} |
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} |
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read_unlock(&tasklist_lock); |
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/* |
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* We found no owner yet mm_users > 1: this implies that we are |
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* most likely racing with swapoff (try_to_unuse()) or /proc or |
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* ptrace or page migration (get_task_mm()). Mark owner as NULL. |
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*/ |
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WRITE_ONCE(mm->owner, NULL); |
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return; |
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|
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assign_new_owner: |
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BUG_ON(c == p); |
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get_task_struct(c); |
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/* |
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* The task_lock protects c->mm from changing. |
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* We always want mm->owner->mm == mm |
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*/ |
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task_lock(c); |
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/* |
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* Delay read_unlock() till we have the task_lock() |
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* to ensure that c does not slip away underneath us |
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*/ |
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read_unlock(&tasklist_lock); |
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if (c->mm != mm) { |
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task_unlock(c); |
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put_task_struct(c); |
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goto retry; |
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} |
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WRITE_ONCE(mm->owner, c); |
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task_unlock(c); |
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put_task_struct(c); |
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} |
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#endif /* CONFIG_MEMCG */ |
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|
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/* |
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* Turn us into a lazy TLB process if we |
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* aren't already.. |
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*/ |
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static void exit_mm(void) |
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{ |
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struct mm_struct *mm = current->mm; |
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struct core_state *core_state; |
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|
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exit_mm_release(current, mm); |
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if (!mm) |
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return; |
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sync_mm_rss(mm); |
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/* |
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* Serialize with any possible pending coredump. |
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* We must hold mmap_lock around checking core_state |
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* and clearing tsk->mm. The core-inducing thread |
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* will increment ->nr_threads for each thread in the |
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* group with ->mm != NULL. |
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*/ |
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mmap_read_lock(mm); |
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core_state = mm->core_state; |
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if (core_state) { |
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struct core_thread self; |
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|
|
mmap_read_unlock(mm); |
|
|
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self.task = current; |
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if (self.task->flags & PF_SIGNALED) |
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self.next = xchg(&core_state->dumper.next, &self); |
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else |
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self.task = NULL; |
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/* |
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* Implies mb(), the result of xchg() must be visible |
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* to core_state->dumper. |
|
*/ |
|
if (atomic_dec_and_test(&core_state->nr_threads)) |
|
complete(&core_state->startup); |
|
|
|
for (;;) { |
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set_current_state(TASK_UNINTERRUPTIBLE); |
|
if (!self.task) /* see coredump_finish() */ |
|
break; |
|
freezable_schedule(); |
|
} |
|
__set_current_state(TASK_RUNNING); |
|
mmap_read_lock(mm); |
|
} |
|
mmgrab(mm); |
|
BUG_ON(mm != current->active_mm); |
|
/* more a memory barrier than a real lock */ |
|
task_lock(current); |
|
/* |
|
* When a thread stops operating on an address space, the loop |
|
* in membarrier_private_expedited() may not observe that |
|
* tsk->mm, and the loop in membarrier_global_expedited() may |
|
* not observe a MEMBARRIER_STATE_GLOBAL_EXPEDITED |
|
* rq->membarrier_state, so those would not issue an IPI. |
|
* Membarrier requires a memory barrier after accessing |
|
* user-space memory, before clearing tsk->mm or the |
|
* rq->membarrier_state. |
|
*/ |
|
smp_mb__after_spinlock(); |
|
local_irq_disable(); |
|
current->mm = NULL; |
|
membarrier_update_current_mm(NULL); |
|
enter_lazy_tlb(mm, current); |
|
local_irq_enable(); |
|
task_unlock(current); |
|
mmap_read_unlock(mm); |
|
mm_update_next_owner(mm); |
|
mmput(mm); |
|
if (test_thread_flag(TIF_MEMDIE)) |
|
exit_oom_victim(); |
|
} |
|
|
|
static struct task_struct *find_alive_thread(struct task_struct *p) |
|
{ |
|
struct task_struct *t; |
|
|
|
for_each_thread(p, t) { |
|
if (!(t->flags & PF_EXITING)) |
|
return t; |
|
} |
|
return NULL; |
|
} |
|
|
|
static struct task_struct *find_child_reaper(struct task_struct *father, |
|
struct list_head *dead) |
|
__releases(&tasklist_lock) |
|
__acquires(&tasklist_lock) |
|
{ |
|
struct pid_namespace *pid_ns = task_active_pid_ns(father); |
|
struct task_struct *reaper = pid_ns->child_reaper; |
|
struct task_struct *p, *n; |
|
|
|
if (likely(reaper != father)) |
|
return reaper; |
|
|
|
reaper = find_alive_thread(father); |
|
if (reaper) { |
|
pid_ns->child_reaper = reaper; |
|
return reaper; |
|
} |
|
|
|
write_unlock_irq(&tasklist_lock); |
|
|
|
list_for_each_entry_safe(p, n, dead, ptrace_entry) { |
|
list_del_init(&p->ptrace_entry); |
|
release_task(p); |
|
} |
|
|
|
zap_pid_ns_processes(pid_ns); |
|
write_lock_irq(&tasklist_lock); |
|
|
|
return father; |
|
} |
|
|
|
/* |
|
* When we die, we re-parent all our children, and try to: |
|
* 1. give them to another thread in our thread group, if such a member exists |
|
* 2. give it to the first ancestor process which prctl'd itself as a |
|
* child_subreaper for its children (like a service manager) |
|
* 3. give it to the init process (PID 1) in our pid namespace |
|
*/ |
|
static struct task_struct *find_new_reaper(struct task_struct *father, |
|
struct task_struct *child_reaper) |
|
{ |
|
struct task_struct *thread, *reaper; |
|
|
|
thread = find_alive_thread(father); |
|
if (thread) |
|
return thread; |
|
|
|
if (father->signal->has_child_subreaper) { |
|
unsigned int ns_level = task_pid(father)->level; |
|
/* |
|
* Find the first ->is_child_subreaper ancestor in our pid_ns. |
|
* We can't check reaper != child_reaper to ensure we do not |
|
* cross the namespaces, the exiting parent could be injected |
|
* by setns() + fork(). |
|
* We check pid->level, this is slightly more efficient than |
|
* task_active_pid_ns(reaper) != task_active_pid_ns(father). |
|
*/ |
|
for (reaper = father->real_parent; |
|
task_pid(reaper)->level == ns_level; |
|
reaper = reaper->real_parent) { |
|
if (reaper == &init_task) |
|
break; |
|
if (!reaper->signal->is_child_subreaper) |
|
continue; |
|
thread = find_alive_thread(reaper); |
|
if (thread) |
|
return thread; |
|
} |
|
} |
|
|
|
return child_reaper; |
|
} |
|
|
|
/* |
|
* Any that need to be release_task'd are put on the @dead list. |
|
*/ |
|
static void reparent_leader(struct task_struct *father, struct task_struct *p, |
|
struct list_head *dead) |
|
{ |
|
if (unlikely(p->exit_state == EXIT_DEAD)) |
|
return; |
|
|
|
/* We don't want people slaying init. */ |
|
p->exit_signal = SIGCHLD; |
|
|
|
/* If it has exited notify the new parent about this child's death. */ |
|
if (!p->ptrace && |
|
p->exit_state == EXIT_ZOMBIE && thread_group_empty(p)) { |
|
if (do_notify_parent(p, p->exit_signal)) { |
|
p->exit_state = EXIT_DEAD; |
|
list_add(&p->ptrace_entry, dead); |
|
} |
|
} |
|
|
|
kill_orphaned_pgrp(p, father); |
|
} |
|
|
|
/* |
|
* This does two things: |
|
* |
|
* A. Make init inherit all the child processes |
|
* B. Check to see if any process groups have become orphaned |
|
* as a result of our exiting, and if they have any stopped |
|
* jobs, send them a SIGHUP and then a SIGCONT. (POSIX 3.2.2.2) |
|
*/ |
|
static void forget_original_parent(struct task_struct *father, |
|
struct list_head *dead) |
|
{ |
|
struct task_struct *p, *t, *reaper; |
|
|
|
if (unlikely(!list_empty(&father->ptraced))) |
|
exit_ptrace(father, dead); |
|
|
|
/* Can drop and reacquire tasklist_lock */ |
|
reaper = find_child_reaper(father, dead); |
|
if (list_empty(&father->children)) |
|
return; |
|
|
|
reaper = find_new_reaper(father, reaper); |
|
list_for_each_entry(p, &father->children, sibling) { |
|
for_each_thread(p, t) { |
|
RCU_INIT_POINTER(t->real_parent, reaper); |
|
BUG_ON((!t->ptrace) != (rcu_access_pointer(t->parent) == father)); |
|
if (likely(!t->ptrace)) |
|
t->parent = t->real_parent; |
|
if (t->pdeath_signal) |
|
group_send_sig_info(t->pdeath_signal, |
|
SEND_SIG_NOINFO, t, |
|
PIDTYPE_TGID); |
|
} |
|
/* |
|
* If this is a threaded reparent there is no need to |
|
* notify anyone anything has happened. |
|
*/ |
|
if (!same_thread_group(reaper, father)) |
|
reparent_leader(father, p, dead); |
|
} |
|
list_splice_tail_init(&father->children, &reaper->children); |
|
} |
|
|
|
/* |
|
* Send signals to all our closest relatives so that they know |
|
* to properly mourn us.. |
|
*/ |
|
static void exit_notify(struct task_struct *tsk, int group_dead) |
|
{ |
|
bool autoreap; |
|
struct task_struct *p, *n; |
|
LIST_HEAD(dead); |
|
|
|
write_lock_irq(&tasklist_lock); |
|
forget_original_parent(tsk, &dead); |
|
|
|
if (group_dead) |
|
kill_orphaned_pgrp(tsk->group_leader, NULL); |
|
|
|
tsk->exit_state = EXIT_ZOMBIE; |
|
if (unlikely(tsk->ptrace)) { |
|
int sig = thread_group_leader(tsk) && |
|
thread_group_empty(tsk) && |
|
!ptrace_reparented(tsk) ? |
|
tsk->exit_signal : SIGCHLD; |
|
autoreap = do_notify_parent(tsk, sig); |
|
} else if (thread_group_leader(tsk)) { |
|
autoreap = thread_group_empty(tsk) && |
|
do_notify_parent(tsk, tsk->exit_signal); |
|
} else { |
|
autoreap = true; |
|
} |
|
|
|
if (autoreap) { |
|
tsk->exit_state = EXIT_DEAD; |
|
list_add(&tsk->ptrace_entry, &dead); |
|
} |
|
|
|
/* mt-exec, de_thread() is waiting for group leader */ |
|
if (unlikely(tsk->signal->notify_count < 0)) |
|
wake_up_process(tsk->signal->group_exit_task); |
|
write_unlock_irq(&tasklist_lock); |
|
|
|
list_for_each_entry_safe(p, n, &dead, ptrace_entry) { |
|
list_del_init(&p->ptrace_entry); |
|
release_task(p); |
|
} |
|
} |
|
|
|
#ifdef CONFIG_DEBUG_STACK_USAGE |
|
static void check_stack_usage(void) |
|
{ |
|
static DEFINE_SPINLOCK(low_water_lock); |
|
static int lowest_to_date = THREAD_SIZE; |
|
unsigned long free; |
|
|
|
free = stack_not_used(current); |
|
|
|
if (free >= lowest_to_date) |
|
return; |
|
|
|
spin_lock(&low_water_lock); |
|
if (free < lowest_to_date) { |
|
pr_info("%s (%d) used greatest stack depth: %lu bytes left\n", |
|
current->comm, task_pid_nr(current), free); |
|
lowest_to_date = free; |
|
} |
|
spin_unlock(&low_water_lock); |
|
} |
|
#else |
|
static inline void check_stack_usage(void) {} |
|
#endif |
|
|
|
void __noreturn do_exit(long code) |
|
{ |
|
struct task_struct *tsk = current; |
|
int group_dead; |
|
|
|
/* |
|
* We can get here from a kernel oops, sometimes with preemption off. |
|
* Start by checking for critical errors. |
|
* Then fix up important state like USER_DS and preemption. |
|
* Then do everything else. |
|
*/ |
|
|
|
WARN_ON(blk_needs_flush_plug(tsk)); |
|
|
|
if (unlikely(in_interrupt())) |
|
panic("Aiee, killing interrupt handler!"); |
|
if (unlikely(!tsk->pid)) |
|
panic("Attempted to kill the idle task!"); |
|
|
|
/* |
|
* If do_exit is called because this processes oopsed, it's possible |
|
* that get_fs() was left as KERNEL_DS, so reset it to USER_DS before |
|
* continuing. Amongst other possible reasons, this is to prevent |
|
* mm_release()->clear_child_tid() from writing to a user-controlled |
|
* kernel address. |
|
*/ |
|
force_uaccess_begin(); |
|
|
|
if (unlikely(in_atomic())) { |
|
pr_info("note: %s[%d] exited with preempt_count %d\n", |
|
current->comm, task_pid_nr(current), |
|
preempt_count()); |
|
preempt_count_set(PREEMPT_ENABLED); |
|
} |
|
|
|
profile_task_exit(tsk); |
|
kcov_task_exit(tsk); |
|
|
|
ptrace_event(PTRACE_EVENT_EXIT, code); |
|
|
|
validate_creds_for_do_exit(tsk); |
|
|
|
/* |
|
* We're taking recursive faults here in do_exit. Safest is to just |
|
* leave this task alone and wait for reboot. |
|
*/ |
|
if (unlikely(tsk->flags & PF_EXITING)) { |
|
pr_alert("Fixing recursive fault but reboot is needed!\n"); |
|
futex_exit_recursive(tsk); |
|
set_current_state(TASK_UNINTERRUPTIBLE); |
|
schedule(); |
|
} |
|
|
|
io_uring_files_cancel(); |
|
exit_signals(tsk); /* sets PF_EXITING */ |
|
|
|
/* sync mm's RSS info before statistics gathering */ |
|
if (tsk->mm) |
|
sync_mm_rss(tsk->mm); |
|
acct_update_integrals(tsk); |
|
group_dead = atomic_dec_and_test(&tsk->signal->live); |
|
if (group_dead) { |
|
/* |
|
* If the last thread of global init has exited, panic |
|
* immediately to get a useable coredump. |
|
*/ |
|
if (unlikely(is_global_init(tsk))) |
|
panic("Attempted to kill init! exitcode=0x%08x\n", |
|
tsk->signal->group_exit_code ?: (int)code); |
|
|
|
#ifdef CONFIG_POSIX_TIMERS |
|
hrtimer_cancel(&tsk->signal->real_timer); |
|
exit_itimers(tsk->signal); |
|
#endif |
|
if (tsk->mm) |
|
setmax_mm_hiwater_rss(&tsk->signal->maxrss, tsk->mm); |
|
} |
|
acct_collect(code, group_dead); |
|
if (group_dead) |
|
tty_audit_exit(); |
|
audit_free(tsk); |
|
|
|
tsk->exit_code = code; |
|
taskstats_exit(tsk, group_dead); |
|
|
|
exit_mm(); |
|
|
|
if (group_dead) |
|
acct_process(); |
|
trace_sched_process_exit(tsk); |
|
|
|
exit_sem(tsk); |
|
exit_shm(tsk); |
|
exit_files(tsk); |
|
exit_fs(tsk); |
|
if (group_dead) |
|
disassociate_ctty(1); |
|
exit_task_namespaces(tsk); |
|
exit_task_work(tsk); |
|
exit_thread(tsk); |
|
|
|
/* |
|
* Flush inherited counters to the parent - before the parent |
|
* gets woken up by child-exit notifications. |
|
* |
|
* because of cgroup mode, must be called before cgroup_exit() |
|
*/ |
|
perf_event_exit_task(tsk); |
|
|
|
sched_autogroup_exit_task(tsk); |
|
cgroup_exit(tsk); |
|
|
|
/* |
|
* FIXME: do that only when needed, using sched_exit tracepoint |
|
*/ |
|
flush_ptrace_hw_breakpoint(tsk); |
|
|
|
exit_tasks_rcu_start(); |
|
exit_notify(tsk, group_dead); |
|
proc_exit_connector(tsk); |
|
mpol_put_task_policy(tsk); |
|
#ifdef CONFIG_FUTEX |
|
if (unlikely(current->pi_state_cache)) |
|
kfree(current->pi_state_cache); |
|
#endif |
|
/* |
|
* Make sure we are holding no locks: |
|
*/ |
|
debug_check_no_locks_held(); |
|
|
|
if (tsk->io_context) |
|
exit_io_context(tsk); |
|
|
|
if (tsk->splice_pipe) |
|
free_pipe_info(tsk->splice_pipe); |
|
|
|
if (tsk->task_frag.page) |
|
put_page(tsk->task_frag.page); |
|
|
|
validate_creds_for_do_exit(tsk); |
|
|
|
check_stack_usage(); |
|
preempt_disable(); |
|
if (tsk->nr_dirtied) |
|
__this_cpu_add(dirty_throttle_leaks, tsk->nr_dirtied); |
|
exit_rcu(); |
|
exit_tasks_rcu_finish(); |
|
|
|
lockdep_free_task(tsk); |
|
do_task_dead(); |
|
} |
|
EXPORT_SYMBOL_GPL(do_exit); |
|
|
|
void complete_and_exit(struct completion *comp, long code) |
|
{ |
|
if (comp) |
|
complete(comp); |
|
|
|
do_exit(code); |
|
} |
|
EXPORT_SYMBOL(complete_and_exit); |
|
|
|
SYSCALL_DEFINE1(exit, int, error_code) |
|
{ |
|
do_exit((error_code&0xff)<<8); |
|
} |
|
|
|
/* |
|
* Take down every thread in the group. This is called by fatal signals |
|
* as well as by sys_exit_group (below). |
|
*/ |
|
void |
|
do_group_exit(int exit_code) |
|
{ |
|
struct signal_struct *sig = current->signal; |
|
|
|
BUG_ON(exit_code & 0x80); /* core dumps don't get here */ |
|
|
|
if (signal_group_exit(sig)) |
|
exit_code = sig->group_exit_code; |
|
else if (!thread_group_empty(current)) { |
|
struct sighand_struct *const sighand = current->sighand; |
|
|
|
spin_lock_irq(&sighand->siglock); |
|
if (signal_group_exit(sig)) |
|
/* Another thread got here before we took the lock. */ |
|
exit_code = sig->group_exit_code; |
|
else { |
|
sig->group_exit_code = exit_code; |
|
sig->flags = SIGNAL_GROUP_EXIT; |
|
zap_other_threads(current); |
|
} |
|
spin_unlock_irq(&sighand->siglock); |
|
} |
|
|
|
do_exit(exit_code); |
|
/* NOTREACHED */ |
|
} |
|
|
|
/* |
|
* this kills every thread in the thread group. Note that any externally |
|
* wait4()-ing process will get the correct exit code - even if this |
|
* thread is not the thread group leader. |
|
*/ |
|
SYSCALL_DEFINE1(exit_group, int, error_code) |
|
{ |
|
do_group_exit((error_code & 0xff) << 8); |
|
/* NOTREACHED */ |
|
return 0; |
|
} |
|
|
|
struct waitid_info { |
|
pid_t pid; |
|
uid_t uid; |
|
int status; |
|
int cause; |
|
}; |
|
|
|
struct wait_opts { |
|
enum pid_type wo_type; |
|
int wo_flags; |
|
struct pid *wo_pid; |
|
|
|
struct waitid_info *wo_info; |
|
int wo_stat; |
|
struct rusage *wo_rusage; |
|
|
|
wait_queue_entry_t child_wait; |
|
int notask_error; |
|
}; |
|
|
|
static int eligible_pid(struct wait_opts *wo, struct task_struct *p) |
|
{ |
|
return wo->wo_type == PIDTYPE_MAX || |
|
task_pid_type(p, wo->wo_type) == wo->wo_pid; |
|
} |
|
|
|
static int |
|
eligible_child(struct wait_opts *wo, bool ptrace, struct task_struct *p) |
|
{ |
|
if (!eligible_pid(wo, p)) |
|
return 0; |
|
|
|
/* |
|
* Wait for all children (clone and not) if __WALL is set or |
|
* if it is traced by us. |
|
*/ |
|
if (ptrace || (wo->wo_flags & __WALL)) |
|
return 1; |
|
|
|
/* |
|
* Otherwise, wait for clone children *only* if __WCLONE is set; |
|
* otherwise, wait for non-clone children *only*. |
|
* |
|
* Note: a "clone" child here is one that reports to its parent |
|
* using a signal other than SIGCHLD, or a non-leader thread which |
|
* we can only see if it is traced by us. |
|
*/ |
|
if ((p->exit_signal != SIGCHLD) ^ !!(wo->wo_flags & __WCLONE)) |
|
return 0; |
|
|
|
return 1; |
|
} |
|
|
|
/* |
|
* Handle sys_wait4 work for one task in state EXIT_ZOMBIE. We hold |
|
* read_lock(&tasklist_lock) on entry. If we return zero, we still hold |
|
* the lock and this task is uninteresting. If we return nonzero, we have |
|
* released the lock and the system call should return. |
|
*/ |
|
static int wait_task_zombie(struct wait_opts *wo, struct task_struct *p) |
|
{ |
|
int state, status; |
|
pid_t pid = task_pid_vnr(p); |
|
uid_t uid = from_kuid_munged(current_user_ns(), task_uid(p)); |
|
struct waitid_info *infop; |
|
|
|
if (!likely(wo->wo_flags & WEXITED)) |
|
return 0; |
|
|
|
if (unlikely(wo->wo_flags & WNOWAIT)) { |
|
status = p->exit_code; |
|
get_task_struct(p); |
|
read_unlock(&tasklist_lock); |
|
sched_annotate_sleep(); |
|
if (wo->wo_rusage) |
|
getrusage(p, RUSAGE_BOTH, wo->wo_rusage); |
|
put_task_struct(p); |
|
goto out_info; |
|
} |
|
/* |
|
* Move the task's state to DEAD/TRACE, only one thread can do this. |
|
*/ |
|
state = (ptrace_reparented(p) && thread_group_leader(p)) ? |
|
EXIT_TRACE : EXIT_DEAD; |
|
if (cmpxchg(&p->exit_state, EXIT_ZOMBIE, state) != EXIT_ZOMBIE) |
|
return 0; |
|
/* |
|
* We own this thread, nobody else can reap it. |
|
*/ |
|
read_unlock(&tasklist_lock); |
|
sched_annotate_sleep(); |
|
|
|
/* |
|
* Check thread_group_leader() to exclude the traced sub-threads. |
|
*/ |
|
if (state == EXIT_DEAD && thread_group_leader(p)) { |
|
struct signal_struct *sig = p->signal; |
|
struct signal_struct *psig = current->signal; |
|
unsigned long maxrss; |
|
u64 tgutime, tgstime; |
|
|
|
/* |
|
* The resource counters for the group leader are in its |
|
* own task_struct. Those for dead threads in the group |
|
* are in its signal_struct, as are those for the child |
|
* processes it has previously reaped. All these |
|
* accumulate in the parent's signal_struct c* fields. |
|
* |
|
* We don't bother to take a lock here to protect these |
|
* p->signal fields because the whole thread group is dead |
|
* and nobody can change them. |
|
* |
|
* psig->stats_lock also protects us from our sub-theads |
|
* which can reap other children at the same time. Until |
|
* we change k_getrusage()-like users to rely on this lock |
|
* we have to take ->siglock as well. |
|
* |
|
* We use thread_group_cputime_adjusted() to get times for |
|
* the thread group, which consolidates times for all threads |
|
* in the group including the group leader. |
|
*/ |
|
thread_group_cputime_adjusted(p, &tgutime, &tgstime); |
|
spin_lock_irq(¤t->sighand->siglock); |
|
write_seqlock(&psig->stats_lock); |
|
psig->cutime += tgutime + sig->cutime; |
|
psig->cstime += tgstime + sig->cstime; |
|
psig->cgtime += task_gtime(p) + sig->gtime + sig->cgtime; |
|
psig->cmin_flt += |
|
p->min_flt + sig->min_flt + sig->cmin_flt; |
|
psig->cmaj_flt += |
|
p->maj_flt + sig->maj_flt + sig->cmaj_flt; |
|
psig->cnvcsw += |
|
p->nvcsw + sig->nvcsw + sig->cnvcsw; |
|
psig->cnivcsw += |
|
p->nivcsw + sig->nivcsw + sig->cnivcsw; |
|
psig->cinblock += |
|
task_io_get_inblock(p) + |
|
sig->inblock + sig->cinblock; |
|
psig->coublock += |
|
task_io_get_oublock(p) + |
|
sig->oublock + sig->coublock; |
|
maxrss = max(sig->maxrss, sig->cmaxrss); |
|
if (psig->cmaxrss < maxrss) |
|
psig->cmaxrss = maxrss; |
|
task_io_accounting_add(&psig->ioac, &p->ioac); |
|
task_io_accounting_add(&psig->ioac, &sig->ioac); |
|
write_sequnlock(&psig->stats_lock); |
|
spin_unlock_irq(¤t->sighand->siglock); |
|
} |
|
|
|
if (wo->wo_rusage) |
|
getrusage(p, RUSAGE_BOTH, wo->wo_rusage); |
|
status = (p->signal->flags & SIGNAL_GROUP_EXIT) |
|
? p->signal->group_exit_code : p->exit_code; |
|
wo->wo_stat = status; |
|
|
|
if (state == EXIT_TRACE) { |
|
write_lock_irq(&tasklist_lock); |
|
/* We dropped tasklist, ptracer could die and untrace */ |
|
ptrace_unlink(p); |
|
|
|
/* If parent wants a zombie, don't release it now */ |
|
state = EXIT_ZOMBIE; |
|
if (do_notify_parent(p, p->exit_signal)) |
|
state = EXIT_DEAD; |
|
p->exit_state = state; |
|
write_unlock_irq(&tasklist_lock); |
|
} |
|
if (state == EXIT_DEAD) |
|
release_task(p); |
|
|
|
out_info: |
|
infop = wo->wo_info; |
|
if (infop) { |
|
if ((status & 0x7f) == 0) { |
|
infop->cause = CLD_EXITED; |
|
infop->status = status >> 8; |
|
} else { |
|
infop->cause = (status & 0x80) ? CLD_DUMPED : CLD_KILLED; |
|
infop->status = status & 0x7f; |
|
} |
|
infop->pid = pid; |
|
infop->uid = uid; |
|
} |
|
|
|
return pid; |
|
} |
|
|
|
static int *task_stopped_code(struct task_struct *p, bool ptrace) |
|
{ |
|
if (ptrace) { |
|
if (task_is_traced(p) && !(p->jobctl & JOBCTL_LISTENING)) |
|
return &p->exit_code; |
|
} else { |
|
if (p->signal->flags & SIGNAL_STOP_STOPPED) |
|
return &p->signal->group_exit_code; |
|
} |
|
return NULL; |
|
} |
|
|
|
/** |
|
* wait_task_stopped - Wait for %TASK_STOPPED or %TASK_TRACED |
|
* @wo: wait options |
|
* @ptrace: is the wait for ptrace |
|
* @p: task to wait for |
|
* |
|
* Handle sys_wait4() work for %p in state %TASK_STOPPED or %TASK_TRACED. |
|
* |
|
* CONTEXT: |
|
* read_lock(&tasklist_lock), which is released if return value is |
|
* non-zero. Also, grabs and releases @p->sighand->siglock. |
|
* |
|
* RETURNS: |
|
* 0 if wait condition didn't exist and search for other wait conditions |
|
* should continue. Non-zero return, -errno on failure and @p's pid on |
|
* success, implies that tasklist_lock is released and wait condition |
|
* search should terminate. |
|
*/ |
|
static int wait_task_stopped(struct wait_opts *wo, |
|
int ptrace, struct task_struct *p) |
|
{ |
|
struct waitid_info *infop; |
|
int exit_code, *p_code, why; |
|
uid_t uid = 0; /* unneeded, required by compiler */ |
|
pid_t pid; |
|
|
|
/* |
|
* Traditionally we see ptrace'd stopped tasks regardless of options. |
|
*/ |
|
if (!ptrace && !(wo->wo_flags & WUNTRACED)) |
|
return 0; |
|
|
|
if (!task_stopped_code(p, ptrace)) |
|
return 0; |
|
|
|
exit_code = 0; |
|
spin_lock_irq(&p->sighand->siglock); |
|
|
|
p_code = task_stopped_code(p, ptrace); |
|
if (unlikely(!p_code)) |
|
goto unlock_sig; |
|
|
|
exit_code = *p_code; |
|
if (!exit_code) |
|
goto unlock_sig; |
|
|
|
if (!unlikely(wo->wo_flags & WNOWAIT)) |
|
*p_code = 0; |
|
|
|
uid = from_kuid_munged(current_user_ns(), task_uid(p)); |
|
unlock_sig: |
|
spin_unlock_irq(&p->sighand->siglock); |
|
if (!exit_code) |
|
return 0; |
|
|
|
/* |
|
* Now we are pretty sure this task is interesting. |
|
* Make sure it doesn't get reaped out from under us while we |
|
* give up the lock and then examine it below. We don't want to |
|
* keep holding onto the tasklist_lock while we call getrusage and |
|
* possibly take page faults for user memory. |
|
*/ |
|
get_task_struct(p); |
|
pid = task_pid_vnr(p); |
|
why = ptrace ? CLD_TRAPPED : CLD_STOPPED; |
|
read_unlock(&tasklist_lock); |
|
sched_annotate_sleep(); |
|
if (wo->wo_rusage) |
|
getrusage(p, RUSAGE_BOTH, wo->wo_rusage); |
|
put_task_struct(p); |
|
|
|
if (likely(!(wo->wo_flags & WNOWAIT))) |
|
wo->wo_stat = (exit_code << 8) | 0x7f; |
|
|
|
infop = wo->wo_info; |
|
if (infop) { |
|
infop->cause = why; |
|
infop->status = exit_code; |
|
infop->pid = pid; |
|
infop->uid = uid; |
|
} |
|
return pid; |
|
} |
|
|
|
/* |
|
* Handle do_wait work for one task in a live, non-stopped state. |
|
* read_lock(&tasklist_lock) on entry. If we return zero, we still hold |
|
* the lock and this task is uninteresting. If we return nonzero, we have |
|
* released the lock and the system call should return. |
|
*/ |
|
static int wait_task_continued(struct wait_opts *wo, struct task_struct *p) |
|
{ |
|
struct waitid_info *infop; |
|
pid_t pid; |
|
uid_t uid; |
|
|
|
if (!unlikely(wo->wo_flags & WCONTINUED)) |
|
return 0; |
|
|
|
if (!(p->signal->flags & SIGNAL_STOP_CONTINUED)) |
|
return 0; |
|
|
|
spin_lock_irq(&p->sighand->siglock); |
|
/* Re-check with the lock held. */ |
|
if (!(p->signal->flags & SIGNAL_STOP_CONTINUED)) { |
|
spin_unlock_irq(&p->sighand->siglock); |
|
return 0; |
|
} |
|
if (!unlikely(wo->wo_flags & WNOWAIT)) |
|
p->signal->flags &= ~SIGNAL_STOP_CONTINUED; |
|
uid = from_kuid_munged(current_user_ns(), task_uid(p)); |
|
spin_unlock_irq(&p->sighand->siglock); |
|
|
|
pid = task_pid_vnr(p); |
|
get_task_struct(p); |
|
read_unlock(&tasklist_lock); |
|
sched_annotate_sleep(); |
|
if (wo->wo_rusage) |
|
getrusage(p, RUSAGE_BOTH, wo->wo_rusage); |
|
put_task_struct(p); |
|
|
|
infop = wo->wo_info; |
|
if (!infop) { |
|
wo->wo_stat = 0xffff; |
|
} else { |
|
infop->cause = CLD_CONTINUED; |
|
infop->pid = pid; |
|
infop->uid = uid; |
|
infop->status = SIGCONT; |
|
} |
|
return pid; |
|
} |
|
|
|
/* |
|
* Consider @p for a wait by @parent. |
|
* |
|
* -ECHILD should be in ->notask_error before the first call. |
|
* Returns nonzero for a final return, when we have unlocked tasklist_lock. |
|
* Returns zero if the search for a child should continue; |
|
* then ->notask_error is 0 if @p is an eligible child, |
|
* or still -ECHILD. |
|
*/ |
|
static int wait_consider_task(struct wait_opts *wo, int ptrace, |
|
struct task_struct *p) |
|
{ |
|
/* |
|
* We can race with wait_task_zombie() from another thread. |
|
* Ensure that EXIT_ZOMBIE -> EXIT_DEAD/EXIT_TRACE transition |
|
* can't confuse the checks below. |
|
*/ |
|
int exit_state = READ_ONCE(p->exit_state); |
|
int ret; |
|
|
|
if (unlikely(exit_state == EXIT_DEAD)) |
|
return 0; |
|
|
|
ret = eligible_child(wo, ptrace, p); |
|
if (!ret) |
|
return ret; |
|
|
|
if (unlikely(exit_state == EXIT_TRACE)) { |
|
/* |
|
* ptrace == 0 means we are the natural parent. In this case |
|
* we should clear notask_error, debugger will notify us. |
|
*/ |
|
if (likely(!ptrace)) |
|
wo->notask_error = 0; |
|
return 0; |
|
} |
|
|
|
if (likely(!ptrace) && unlikely(p->ptrace)) { |
|
/* |
|
* If it is traced by its real parent's group, just pretend |
|
* the caller is ptrace_do_wait() and reap this child if it |
|
* is zombie. |
|
* |
|
* This also hides group stop state from real parent; otherwise |
|
* a single stop can be reported twice as group and ptrace stop. |
|
* If a ptracer wants to distinguish these two events for its |
|
* own children it should create a separate process which takes |
|
* the role of real parent. |
|
*/ |
|
if (!ptrace_reparented(p)) |
|
ptrace = 1; |
|
} |
|
|
|
/* slay zombie? */ |
|
if (exit_state == EXIT_ZOMBIE) { |
|
/* we don't reap group leaders with subthreads */ |
|
if (!delay_group_leader(p)) { |
|
/* |
|
* A zombie ptracee is only visible to its ptracer. |
|
* Notification and reaping will be cascaded to the |
|
* real parent when the ptracer detaches. |
|
*/ |
|
if (unlikely(ptrace) || likely(!p->ptrace)) |
|
return wait_task_zombie(wo, p); |
|
} |
|
|
|
/* |
|
* Allow access to stopped/continued state via zombie by |
|
* falling through. Clearing of notask_error is complex. |
|
* |
|
* When !@ptrace: |
|
* |
|
* If WEXITED is set, notask_error should naturally be |
|
* cleared. If not, subset of WSTOPPED|WCONTINUED is set, |
|
* so, if there are live subthreads, there are events to |
|
* wait for. If all subthreads are dead, it's still safe |
|
* to clear - this function will be called again in finite |
|
* amount time once all the subthreads are released and |
|
* will then return without clearing. |
|
* |
|
* When @ptrace: |
|
* |
|
* Stopped state is per-task and thus can't change once the |
|
* target task dies. Only continued and exited can happen. |
|
* Clear notask_error if WCONTINUED | WEXITED. |
|
*/ |
|
if (likely(!ptrace) || (wo->wo_flags & (WCONTINUED | WEXITED))) |
|
wo->notask_error = 0; |
|
} else { |
|
/* |
|
* @p is alive and it's gonna stop, continue or exit, so |
|
* there always is something to wait for. |
|
*/ |
|
wo->notask_error = 0; |
|
} |
|
|
|
/* |
|
* Wait for stopped. Depending on @ptrace, different stopped state |
|
* is used and the two don't interact with each other. |
|
*/ |
|
ret = wait_task_stopped(wo, ptrace, p); |
|
if (ret) |
|
return ret; |
|
|
|
/* |
|
* Wait for continued. There's only one continued state and the |
|
* ptracer can consume it which can confuse the real parent. Don't |
|
* use WCONTINUED from ptracer. You don't need or want it. |
|
*/ |
|
return wait_task_continued(wo, p); |
|
} |
|
|
|
/* |
|
* Do the work of do_wait() for one thread in the group, @tsk. |
|
* |
|
* -ECHILD should be in ->notask_error before the first call. |
|
* Returns nonzero for a final return, when we have unlocked tasklist_lock. |
|
* Returns zero if the search for a child should continue; then |
|
* ->notask_error is 0 if there were any eligible children, |
|
* or still -ECHILD. |
|
*/ |
|
static int do_wait_thread(struct wait_opts *wo, struct task_struct *tsk) |
|
{ |
|
struct task_struct *p; |
|
|
|
list_for_each_entry(p, &tsk->children, sibling) { |
|
int ret = wait_consider_task(wo, 0, p); |
|
|
|
if (ret) |
|
return ret; |
|
} |
|
|
|
return 0; |
|
} |
|
|
|
static int ptrace_do_wait(struct wait_opts *wo, struct task_struct *tsk) |
|
{ |
|
struct task_struct *p; |
|
|
|
list_for_each_entry(p, &tsk->ptraced, ptrace_entry) { |
|
int ret = wait_consider_task(wo, 1, p); |
|
|
|
if (ret) |
|
return ret; |
|
} |
|
|
|
return 0; |
|
} |
|
|
|
static int child_wait_callback(wait_queue_entry_t *wait, unsigned mode, |
|
int sync, void *key) |
|
{ |
|
struct wait_opts *wo = container_of(wait, struct wait_opts, |
|
child_wait); |
|
struct task_struct *p = key; |
|
|
|
if (!eligible_pid(wo, p)) |
|
return 0; |
|
|
|
if ((wo->wo_flags & __WNOTHREAD) && wait->private != p->parent) |
|
return 0; |
|
|
|
return default_wake_function(wait, mode, sync, key); |
|
} |
|
|
|
void __wake_up_parent(struct task_struct *p, struct task_struct *parent) |
|
{ |
|
__wake_up_sync_key(&parent->signal->wait_chldexit, |
|
TASK_INTERRUPTIBLE, p); |
|
} |
|
|
|
static bool is_effectively_child(struct wait_opts *wo, bool ptrace, |
|
struct task_struct *target) |
|
{ |
|
struct task_struct *parent = |
|
!ptrace ? target->real_parent : target->parent; |
|
|
|
return current == parent || (!(wo->wo_flags & __WNOTHREAD) && |
|
same_thread_group(current, parent)); |
|
} |
|
|
|
/* |
|
* Optimization for waiting on PIDTYPE_PID. No need to iterate through child |
|
* and tracee lists to find the target task. |
|
*/ |
|
static int do_wait_pid(struct wait_opts *wo) |
|
{ |
|
bool ptrace; |
|
struct task_struct *target; |
|
int retval; |
|
|
|
ptrace = false; |
|
target = pid_task(wo->wo_pid, PIDTYPE_TGID); |
|
if (target && is_effectively_child(wo, ptrace, target)) { |
|
retval = wait_consider_task(wo, ptrace, target); |
|
if (retval) |
|
return retval; |
|
} |
|
|
|
ptrace = true; |
|
target = pid_task(wo->wo_pid, PIDTYPE_PID); |
|
if (target && target->ptrace && |
|
is_effectively_child(wo, ptrace, target)) { |
|
retval = wait_consider_task(wo, ptrace, target); |
|
if (retval) |
|
return retval; |
|
} |
|
|
|
return 0; |
|
} |
|
|
|
static long do_wait(struct wait_opts *wo) |
|
{ |
|
int retval; |
|
|
|
trace_sched_process_wait(wo->wo_pid); |
|
|
|
init_waitqueue_func_entry(&wo->child_wait, child_wait_callback); |
|
wo->child_wait.private = current; |
|
add_wait_queue(¤t->signal->wait_chldexit, &wo->child_wait); |
|
repeat: |
|
/* |
|
* If there is nothing that can match our criteria, just get out. |
|
* We will clear ->notask_error to zero if we see any child that |
|
* might later match our criteria, even if we are not able to reap |
|
* it yet. |
|
*/ |
|
wo->notask_error = -ECHILD; |
|
if ((wo->wo_type < PIDTYPE_MAX) && |
|
(!wo->wo_pid || !pid_has_task(wo->wo_pid, wo->wo_type))) |
|
goto notask; |
|
|
|
set_current_state(TASK_INTERRUPTIBLE); |
|
read_lock(&tasklist_lock); |
|
|
|
if (wo->wo_type == PIDTYPE_PID) { |
|
retval = do_wait_pid(wo); |
|
if (retval) |
|
goto end; |
|
} else { |
|
struct task_struct *tsk = current; |
|
|
|
do { |
|
retval = do_wait_thread(wo, tsk); |
|
if (retval) |
|
goto end; |
|
|
|
retval = ptrace_do_wait(wo, tsk); |
|
if (retval) |
|
goto end; |
|
|
|
if (wo->wo_flags & __WNOTHREAD) |
|
break; |
|
} while_each_thread(current, tsk); |
|
} |
|
read_unlock(&tasklist_lock); |
|
|
|
notask: |
|
retval = wo->notask_error; |
|
if (!retval && !(wo->wo_flags & WNOHANG)) { |
|
retval = -ERESTARTSYS; |
|
if (!signal_pending(current)) { |
|
schedule(); |
|
goto repeat; |
|
} |
|
} |
|
end: |
|
__set_current_state(TASK_RUNNING); |
|
remove_wait_queue(¤t->signal->wait_chldexit, &wo->child_wait); |
|
return retval; |
|
} |
|
|
|
static long kernel_waitid(int which, pid_t upid, struct waitid_info *infop, |
|
int options, struct rusage *ru) |
|
{ |
|
struct wait_opts wo; |
|
struct pid *pid = NULL; |
|
enum pid_type type; |
|
long ret; |
|
unsigned int f_flags = 0; |
|
|
|
if (options & ~(WNOHANG|WNOWAIT|WEXITED|WSTOPPED|WCONTINUED| |
|
__WNOTHREAD|__WCLONE|__WALL)) |
|
return -EINVAL; |
|
if (!(options & (WEXITED|WSTOPPED|WCONTINUED))) |
|
return -EINVAL; |
|
|
|
switch (which) { |
|
case P_ALL: |
|
type = PIDTYPE_MAX; |
|
break; |
|
case P_PID: |
|
type = PIDTYPE_PID; |
|
if (upid <= 0) |
|
return -EINVAL; |
|
|
|
pid = find_get_pid(upid); |
|
break; |
|
case P_PGID: |
|
type = PIDTYPE_PGID; |
|
if (upid < 0) |
|
return -EINVAL; |
|
|
|
if (upid) |
|
pid = find_get_pid(upid); |
|
else |
|
pid = get_task_pid(current, PIDTYPE_PGID); |
|
break; |
|
case P_PIDFD: |
|
type = PIDTYPE_PID; |
|
if (upid < 0) |
|
return -EINVAL; |
|
|
|
pid = pidfd_get_pid(upid, &f_flags); |
|
if (IS_ERR(pid)) |
|
return PTR_ERR(pid); |
|
|
|
break; |
|
default: |
|
return -EINVAL; |
|
} |
|
|
|
wo.wo_type = type; |
|
wo.wo_pid = pid; |
|
wo.wo_flags = options; |
|
wo.wo_info = infop; |
|
wo.wo_rusage = ru; |
|
if (f_flags & O_NONBLOCK) |
|
wo.wo_flags |= WNOHANG; |
|
|
|
ret = do_wait(&wo); |
|
if (!ret && !(options & WNOHANG) && (f_flags & O_NONBLOCK)) |
|
ret = -EAGAIN; |
|
|
|
put_pid(pid); |
|
return ret; |
|
} |
|
|
|
SYSCALL_DEFINE5(waitid, int, which, pid_t, upid, struct siginfo __user *, |
|
infop, int, options, struct rusage __user *, ru) |
|
{ |
|
struct rusage r; |
|
struct waitid_info info = {.status = 0}; |
|
long err = kernel_waitid(which, upid, &info, options, ru ? &r : NULL); |
|
int signo = 0; |
|
|
|
if (err > 0) { |
|
signo = SIGCHLD; |
|
err = 0; |
|
if (ru && copy_to_user(ru, &r, sizeof(struct rusage))) |
|
return -EFAULT; |
|
} |
|
if (!infop) |
|
return err; |
|
|
|
if (!user_write_access_begin(infop, sizeof(*infop))) |
|
return -EFAULT; |
|
|
|
unsafe_put_user(signo, &infop->si_signo, Efault); |
|
unsafe_put_user(0, &infop->si_errno, Efault); |
|
unsafe_put_user(info.cause, &infop->si_code, Efault); |
|
unsafe_put_user(info.pid, &infop->si_pid, Efault); |
|
unsafe_put_user(info.uid, &infop->si_uid, Efault); |
|
unsafe_put_user(info.status, &infop->si_status, Efault); |
|
user_write_access_end(); |
|
return err; |
|
Efault: |
|
user_write_access_end(); |
|
return -EFAULT; |
|
} |
|
|
|
long kernel_wait4(pid_t upid, int __user *stat_addr, int options, |
|
struct rusage *ru) |
|
{ |
|
struct wait_opts wo; |
|
struct pid *pid = NULL; |
|
enum pid_type type; |
|
long ret; |
|
|
|
if (options & ~(WNOHANG|WUNTRACED|WCONTINUED| |
|
__WNOTHREAD|__WCLONE|__WALL)) |
|
return -EINVAL; |
|
|
|
/* -INT_MIN is not defined */ |
|
if (upid == INT_MIN) |
|
return -ESRCH; |
|
|
|
if (upid == -1) |
|
type = PIDTYPE_MAX; |
|
else if (upid < 0) { |
|
type = PIDTYPE_PGID; |
|
pid = find_get_pid(-upid); |
|
} else if (upid == 0) { |
|
type = PIDTYPE_PGID; |
|
pid = get_task_pid(current, PIDTYPE_PGID); |
|
} else /* upid > 0 */ { |
|
type = PIDTYPE_PID; |
|
pid = find_get_pid(upid); |
|
} |
|
|
|
wo.wo_type = type; |
|
wo.wo_pid = pid; |
|
wo.wo_flags = options | WEXITED; |
|
wo.wo_info = NULL; |
|
wo.wo_stat = 0; |
|
wo.wo_rusage = ru; |
|
ret = do_wait(&wo); |
|
put_pid(pid); |
|
if (ret > 0 && stat_addr && put_user(wo.wo_stat, stat_addr)) |
|
ret = -EFAULT; |
|
|
|
return ret; |
|
} |
|
|
|
int kernel_wait(pid_t pid, int *stat) |
|
{ |
|
struct wait_opts wo = { |
|
.wo_type = PIDTYPE_PID, |
|
.wo_pid = find_get_pid(pid), |
|
.wo_flags = WEXITED, |
|
}; |
|
int ret; |
|
|
|
ret = do_wait(&wo); |
|
if (ret > 0 && wo.wo_stat) |
|
*stat = wo.wo_stat; |
|
put_pid(wo.wo_pid); |
|
return ret; |
|
} |
|
|
|
SYSCALL_DEFINE4(wait4, pid_t, upid, int __user *, stat_addr, |
|
int, options, struct rusage __user *, ru) |
|
{ |
|
struct rusage r; |
|
long err = kernel_wait4(upid, stat_addr, options, ru ? &r : NULL); |
|
|
|
if (err > 0) { |
|
if (ru && copy_to_user(ru, &r, sizeof(struct rusage))) |
|
return -EFAULT; |
|
} |
|
return err; |
|
} |
|
|
|
#ifdef __ARCH_WANT_SYS_WAITPID |
|
|
|
/* |
|
* sys_waitpid() remains for compatibility. waitpid() should be |
|
* implemented by calling sys_wait4() from libc.a. |
|
*/ |
|
SYSCALL_DEFINE3(waitpid, pid_t, pid, int __user *, stat_addr, int, options) |
|
{ |
|
return kernel_wait4(pid, stat_addr, options, NULL); |
|
} |
|
|
|
#endif |
|
|
|
#ifdef CONFIG_COMPAT |
|
COMPAT_SYSCALL_DEFINE4(wait4, |
|
compat_pid_t, pid, |
|
compat_uint_t __user *, stat_addr, |
|
int, options, |
|
struct compat_rusage __user *, ru) |
|
{ |
|
struct rusage r; |
|
long err = kernel_wait4(pid, stat_addr, options, ru ? &r : NULL); |
|
if (err > 0) { |
|
if (ru && put_compat_rusage(&r, ru)) |
|
return -EFAULT; |
|
} |
|
return err; |
|
} |
|
|
|
COMPAT_SYSCALL_DEFINE5(waitid, |
|
int, which, compat_pid_t, pid, |
|
struct compat_siginfo __user *, infop, int, options, |
|
struct compat_rusage __user *, uru) |
|
{ |
|
struct rusage ru; |
|
struct waitid_info info = {.status = 0}; |
|
long err = kernel_waitid(which, pid, &info, options, uru ? &ru : NULL); |
|
int signo = 0; |
|
if (err > 0) { |
|
signo = SIGCHLD; |
|
err = 0; |
|
if (uru) { |
|
/* kernel_waitid() overwrites everything in ru */ |
|
if (COMPAT_USE_64BIT_TIME) |
|
err = copy_to_user(uru, &ru, sizeof(ru)); |
|
else |
|
err = put_compat_rusage(&ru, uru); |
|
if (err) |
|
return -EFAULT; |
|
} |
|
} |
|
|
|
if (!infop) |
|
return err; |
|
|
|
if (!user_write_access_begin(infop, sizeof(*infop))) |
|
return -EFAULT; |
|
|
|
unsafe_put_user(signo, &infop->si_signo, Efault); |
|
unsafe_put_user(0, &infop->si_errno, Efault); |
|
unsafe_put_user(info.cause, &infop->si_code, Efault); |
|
unsafe_put_user(info.pid, &infop->si_pid, Efault); |
|
unsafe_put_user(info.uid, &infop->si_uid, Efault); |
|
unsafe_put_user(info.status, &infop->si_status, Efault); |
|
user_write_access_end(); |
|
return err; |
|
Efault: |
|
user_write_access_end(); |
|
return -EFAULT; |
|
} |
|
#endif |
|
|
|
/** |
|
* thread_group_exited - check that a thread group has exited |
|
* @pid: tgid of thread group to be checked. |
|
* |
|
* Test if the thread group represented by tgid has exited (all |
|
* threads are zombies, dead or completely gone). |
|
* |
|
* Return: true if the thread group has exited. false otherwise. |
|
*/ |
|
bool thread_group_exited(struct pid *pid) |
|
{ |
|
struct task_struct *task; |
|
bool exited; |
|
|
|
rcu_read_lock(); |
|
task = pid_task(pid, PIDTYPE_PID); |
|
exited = !task || |
|
(READ_ONCE(task->exit_state) && thread_group_empty(task)); |
|
rcu_read_unlock(); |
|
|
|
return exited; |
|
} |
|
EXPORT_SYMBOL(thread_group_exited); |
|
|
|
__weak void abort(void) |
|
{ |
|
BUG(); |
|
|
|
/* if that doesn't kill us, halt */ |
|
panic("Oops failed to kill thread"); |
|
} |
|
EXPORT_SYMBOL(abort);
|
|
|